In the winding of textile yarns, it is well known to guide the yarns to rotating cores while traversing the yarn guides axially of the cores to form windings of the yarns about the cores. Such winding of textile yarns frequently results in a particularly acute problem which is referred to as "pattern formation." With increasing package diameter, this problem exists where the windings of yarn are superimposed on previously formed windings so as to directly overlie the same. Such pattern formation invariably occurs when the ratio of package revolutions per time unit (e.g. revolutions per minute) to the double stroke (a complete reciprocation, i.e. over and back) rate of the traversing yarn guide (e.g. reciprocations per minute) is equal to one or an integral multiple thereof.
Pattern formation in textile yarn packages results in trouble when unwinding the packages. Further, such patterns cause the winder to oscillate during formation of the packages and thus the drive rolls contact the packages unevenly which frequently results in slippage between the drive rolls and the packages causing damage to the packages. Therefore, pattern formation should be particularly avoided when processing smooth yarns, such as synthetic fibers or filaments.
Since pattern formation is known to occur when the ratio between package speed and traverse motion speed (or vice versa) is equal to an integer of a whole number other than zero, it has previously been proposed that either the package speed or traverse winder speed be changed in an attempt to ensure that such a ratio does not occur. It is particularly desirable to maintain the package speed as nearly constant as possible, particularly when processing synthetic fibers or filaments. Accordingly, previous attempts to avoid pattern formation have generally been directed toward changing the traverse motion speed or double stroke rate.
It is known to control the traverse motion of the yarn guide in such a manner that the aforementioned ratio does not result in an integer other than zero. This is accomplished by changing the traverse motion speed shortly before an integral ratio is reached. While effective, this previous attempt to solve this problem is not technically and economically feasible since a textile machine nearly always includes a multiplicity of winding positions, which have different package diameters at any given time. This means that, basically, the traverse motion speed can only be varied, in this previous proposal, with individually driven package positions and that, even then, each winding position must include package diameter sensor, a programmer and control device for changing the traverse motion speed.
It has also been proposed as an attempt to avoid or at least lessen the pattern formation to employ "wobbling" in the traverse motion speed or constant acceleration or deceleration between a minimum speed and a maximum speed (wobble range). Usually this wobble range varies from about .+-.1% to .+-.20% of the desired average traverse motion speed. However, this attempt does not effectively avoid pattern formation but only prolongs the time period within the winding cycle when pattern formation can be observed since the acceleration and deceleration occur periodically in accordance with a predetermined pattern (such as sine wave, sawtooth pattern, etc.). For example, the double stroke rate per minute on currently used winding machines ranges from several hundred to several thousand and it has been observed that a fourth degree pattern developed within a time interval of one minute without any pattern breaking means, whereas with wobbling means the same pattern was observed after a time interval of eight (8) minutes.